X-ray tube



May 27, 1924. 1,495,533

o. A. ROENSCH X-RAY TUBE Filed Jan. 4, 1919 nvewto c W0 JiRw/m'kPatented ay 27, 1924.

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OTTO A. ROENSCH, OF NEWARK, NEW JERSEY.

X-RAY TUBE.

Application filed. January 4, 1919. Serial No. 269,589.

State of New Jersey, have invented certain new and useful Improvementsin X-Ray Tubes, set forth in the following specification.

The object of this invention is to prolong the life of an X-ray tubeparticularly by shielding static electricity and lateral bombardment inthe vicinity of the cathode. To the above ends employment is made of atubular static shield of conducting material mounted in a novel mannerto increase its insulation and facility in mounting.

These objects will be better understood by reference to the followingspecification, descriptive of an illustrative embodiment of theinvention, which is shown for purposes of illustration only in theaccompanying drawings, forming a part hereof, and in which likecharacters designate corresponding parts in the several figures. In thedrawings Fig. 1 is a side elevation of a preferred form of theinvention;

Fig. 2 is a longitudinal vertical section with parts broken away anddrawn to an enlarged scale; and

Fig. 3 is a perspective view of the preferred embodiment of the staticshield.

The X-ray tube A comprisesthe usual globular central portion 1, anddesired adjuncts such as the vacuum regulator 2 and the auxiliary anode3 and two alined tubular extensions forming a part of the hermeticalclosure. These are the anode extension 13 and the cathode extension C.An anode 4 of approved construction, preferably mounted on a hollowmetallic stemv 5 suitably fixed within the extension B, is provided.

The principal features of the invention are exemplified in the cathodestructure.

The outer glass tube 6 has the usual end closure 7 through which thelead-in wire is sealed. Suitably attached, as by fusing at approximatelythe extreme end of the outer extension 6, is a double tubular support 9.Of this double support both the shield support 10 and the cathodesupport 11 are coaxial with the outer extension 6. They extend inwardlytowards the globe 1. The cathode support is preferably provided with therear flange 12 sealed to the shield support 10 slightly inwardly fromthe seal 13 of the shield support. Both these supports are preferablyimperforate and are fabricaiied' from glass having high insulatingva ue.

path for current flow in the tube, which These imperforate tubeseffectively shield the stem 18 against serving as a by' is localized atthe dish-shaped cathode proper 16.

The dish-shaped cathode proper 16 has a cylindrical stem 17 into whichis axially mounted a cylindrical conductor 18. The

parts 16, 17 and 18 are preferably of alumi-' num, a split sleeve 19,preferably of steelbeing rlveted to the stem 17, and then slipped andsprung about the inner end of the glass support 11, in which manner asecure mounting is obtained, with no danger of local stresses.

The static shield D comprises a metal ring 20 of internal diameterslightly larger than the cathode cup 16, andless than that of the throat24, and extending rearwardly into a gripping sleeve 21, preferablyprovided with slots 22 and 23 to facilitate an easyadjustment andmounting upon the support 10. It should be noted that the rim of thecathode 16 is much nearer to the rim of the shield 20 than is the rim ofthe shield 20 to the glass throat 24. This proportioning of separationeffectively shields the throat 24: as well as centralizes the cathodestream;

It should be noted that the static shield D, which in the operation ofthe tube acquires the same potential as the cathode tending tocentralize the cathode stream, is effectively insulated againstconduction to the walls of the tube, and is effective in protecting thethroat of the glass structure as at 24. It is preferable that the beamof the shield D be .located at least twice as far from the portion 2tofextension C as it is from the cathode 16.

What I claim and desire to secure by United States Letters Patent is 1.In an X-ray tube, in combination with its enclosing wall formed with atubular extension forming the cathode stem and provided with anenclosure; a large co-axial tubular support of glass attached at its farend of said cathode stem at the end closure the cathode stem at theinner end of said first mentioned tubular stem.

2. In an X-ray tube, a lateral tubular extension of glass closed at itsouter end; a double coaxial tubular support attached at its far end tothe end of said extension at its said closed end and having an innercathode supporting portion and an overlapping shield supporting portion;a cathode secured. to the inner end of said cathode supporting portion;and a static shield surrounding said cathode out of contact therewithand mount ed on the end of said shield supporting portion.

3. In an X-ray tube, the combination with its enclosing Wall formed witha tubular extension forming the cathode stem, and a cathode located insaid stem and extending at its head within the neck portion thereof, ofa barrier device located within said stein and surrounding said cathodewith its free end presenting a metal portion located within said stemand surrounding said oath ode, said metal portion being out ofelectrical contact with said cathode and the side wall of said stembeing free of interruptions and projecting parts whereby the continuity01 said stem is unimpaired.

4%. In an X-ray tube, the combination with its enclosing wall forn'iedwith a tubular extension forming the cathode stern, and a cathodelocated in said stem and extending at its head within the neck portionthereof, of a barrier device located within said stem and surroundingsaid cathode, said device being directly connected with a portion of thetube other than said enclosing wall with its free end presenting a metalportion located within said stem and surrounding said cathode, saidinetal portion being out of electrical contact with said cathode and theSite wall of said stein being tree of interruptions and projectingparts, whereby the continuity of said stem is unimpaired.

5. In an X-ray tube the combination with its enclosing wall formed witha tubular extension forming the cathode stern, and a cathode located insaid stem and extending at its head Within the neck portion thereo of abarrier device located within said stern and surrounding said cathodeand supported from the end wall of said stem with its free endpresenting a metal portion located within said stem and surrounding saidcathode, and out of electrical contact with said cathode, whereby theside wall of said stem is free of interruptions and projecting parts andits continuity thus unimpaired.

6. In an X-ray tube, the combination with its enclosing wall formed witha tubular er: tension forming the cathode stem, a cathode supportlocated within said stem and supported from the end wall of said stem,and a cathode on said support, the head of said cathode being Within theneck portion of said stern, of a barrier device supported on saidcathode support and located within said stem and surrounding saidcathode with its free end presenting a metal portion located within saidstem and sin-rounding said cathode, said metal portion being out ofelectrical contact with said cathode.

7. In an X-ray tube, the combination with its enclosing wall torniedwith a tubular e. L tension forming the cathode stein, a cathode supportwithin said stem, and a cathode on said support and within the neckportion of said stem, of a barrier device formed of a tubular membersurrounding, and secured at one end to, said cathode support, with itsfree end presenting a metal portion located within said stem andsurrounding said catlr ode, said metal portion being out of electri calcontact with said cathode.

S. In an X-rny tubeQthe combination with its enclosii'ig wall formedwith a tubular extension torniing the cathode stern, and a cathodelocated in said stern and extending at its head Within the neck portionthereof, of a barrierdevice located Within said stem and surroundingsaid cathode, the space be tween, said cathode stern and the partstherein extending substantially to the outer end of said stem and opento the passage of gas thereinto circulated by the operation of the tube,the wall. of said; barrier device ex tending substantially parallel withthe sur rounding portion of said enclosing wall for a distance greaterthan one-half the length of said extension.

In testimony whereof I have signed my name to this specification, this3rd day of January, 1919.

' OTTO A, ROENSCH,

